Improved Dynamic Properties of Charge-Transfer-Type Supramolecular Rotor Composed of Coronene and F4TCNQ

A charge-transfer (CT)-type supramolecular rotor, (coronene)2F4TCNQ, was obtained by vacuum co-sublimation. The CT complex has an unprecedented crystal structure consisting only of DDA-type alternating π-columns of coronene (D) and electron acceptor (A), and coronene molecules with a pronounced undulating structure form no C–H···F hydrogen bonds with adjacent F4TCNQ molecules in the side-by-side direction. These structural features are in contrast with those reported for (coronene)­F4TCNQ that has DA-type alternating π-columns, which was obtained by diffusion in dichloromethane/pentane. Coronene molecules in the present complex undergo an in-plane rotation in the gigahertz region at 233 K, which is 3 orders of magnitude faster than that in (coronene)­F4TCNQ. Furthermore, the activation energy for the rotation was found to be about half of the value reported for (coronene)­F4TCNQ. These results clearly demonstrate that dynamic properties of the assemblies (CT complexes) can be varied by changing the assembly method (crystallization method), even when the parts (molecules) used as rotator and stator components are the same.